This invention relates generally to performance enhancing systems for internal combustion engines used in automobiles. More specifically, this invention relates to a turbocharger that uses a novel turbine drive source for driving the compressor at a power-enhancement or boost level regardless of the engine exhaust output level.
Many techniques have been devised to increase the performance of automotive internal combustion engines. Supercharger and turbocharger systems have been developed that substantially boost engine performance. These systems operate to increase air pressure delivered to the intake manifold of the engine before being mixed with the fuel. The increased air pressure enhances the combustibility of the fuel, thus making it more powerful. This added power then increases engine power and torque at both lower and higher rpms than would otherwise be possible.
Superchargers and turbochargers typically derive their operating power from the engine. For example, the supercharger, which is an active performance boosting device, uses the engine to turn complicated belts and pulleys, thereby turning successive compressor stages to compress the intake air before introduction into the engine. This allows the supercharger to deliver nearly instantaneous improved engine performance. The belts and pulleys require for operation as much as 40% of the engine's power output, which exacts a price of shortening the engine's life span for the increased performance.
Turbochargers, on the other hand, are passive performance boosting devices that are driven by the exhaust from the engine. The passive design of the turbocharger does not adversely affect the life span of the engine to the degree that a supercharger does. A typical turbocharger has a turbine wheel and a compressor mounted on the same shaft. Fan blades are attached to the turbine wheel, which is placed in the path of the exhaust gases from the engine. The exhaust gases drive the turbine wheel, which then turns the drive shaft. As the drive shaft turns, the compressor fan acts to impel ambient air into a compressor channel, thereby compressing the air. Since the turbocharger is powered by the engine exhaust gases, little to no power boost is available at idle or low speeds since the engine does not generate sufficient enough exhaust force to turn the turbine to compress the air. This condition is known as turbo lag, which means that no extra performance boost is available until the engine is operating at an rpm level high enough to drive the turbocharger fast enough to compress the air for enhancing performance.
Several solutions have been developed to overcome the problem of turbo lag. One solution combines a supercharger with a turbocharger. The supercharger drives the turbocharger until the engine has reached a threshold level at which point it takes over the supercharger's job. This has the advantage of limiting the use of the supercharger, but it also has the drawback of being an active system that shortens engine life, as well as being overly complex.
Another solution is to add a motor to turn the turbocharger shaft until the engine exhaust can take over. The problem with this design is that the motor must drive the shaft at a level exceeding 100,000 rpms. Such motors demand a high electrical load and are very expensive. Also, they are prone to failure due to the high demands placed on them.
Accordingly, what is needed is a turbocharger system that eliminates turbo lag inherent in turbocharger systems. This should be done without resorting to direct drive systems that are prone to failure. Nor should additional compressor stages be required to eliminate turbo lag.